Privilege escalation affecting Microsoft Active Directory Certificate Services
A vulnerability affecting Microsoft Active Directory Certificate Services would allow an authenticated attacker to elevate privileges on affected systems.
Description
Technical context and vulnerability details
Microsoft Active Directory Certificate Services (AD CS) is an identity management service developed by Microsoft, widely deployed in enterprise environments for issuing digital certificates and securing network access. This service is affected by a vulnerability labeled CVE-2026-54121 resulting from insufficient rights control when issuing a certificate. Exploitation of this vulnerability would allow a malicious actor, with a simple user account, to send a specially crafted certificate request to impersonate a domain controller and elevate their privileges on the affected server. It is classified high with a severity score of 8.8 according to CVSS V3.1.
Potential Risks & Impact
Potential consequences upon exploitation
- Privilege escalation;
- Complete takeover of infrastructure;
- Breach of confidentiality and availability of data;
- Compromise of system integrity;
Affected systems
Products, components and targeted versions
- Windows Server 2025 versions earlier than 10.0.26100.33158 running the Active Directory Certificate Services (AD CS) role;
- Windows Server 2022 versions earlier than 10.0.20348.5386 running the AD CS role;
- Windows Server 2019 versions earlier than 10.0.17763.9020 running the AD CS role;
- Windows Server 2016 versions earlier than 10.0.14393.9339 running the AD CS role;
- Versions of Windows Server 2012 and Windows Server 2012 R2 running the AD CS role;
- Windows 10 1607 versions earlier than 10.0.14393.9339;
- Windows 10 1809 versions earlier than 10.0.17763.9020;
Recommended Remediations & Actions
Immediate actions and recommended mitigations
- Update Microsoft Windows systems to the latest stable version available;
Sources & External Links
Vendor security advisories and documentation
Advisory Specifications
CSIRT Emergency Response
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